Simple jQ to close alert messages

It is not important but when the user gets an alert, specially the error with the "X" feels like it should be closable.
e.g. In Authentication > Create an account > add a wrong email and click "Create an account".
close alert messages

It is not important but when the user gets an alert, specially the error with the "X" feels like it should be closable.
e.g. In Authentication > Create an account > add a wrong email and click "Create an account”.
Merge pull request #2135 from elationbase/1.6

[*] FO : Close alert messages